Biomedical subjects

C Robert

Publications and source records attributed to C Robert.

At least 37 records · Page 2Linked to original sources

PubMed2001

Interspecies H2 transfer in cellulose degradation between fibrolytic bacteria and H2-utilizing microorganisms from the human colon.

Interspecies H2 transfer between two newly isolated fibrolytic strains (18P13 and 18P16) and H2-utilizing methanogen or acetogen from the human colon was investigated during in vitro cellulose degradation. Both H2-consuming microorganisms utilized efficiently H2 produced from cellulose fermentation by the fibrolytic species. H2 utilization by Methanobrevibacter smithii did not change the metabolism and the cellulolytic activity of strain 18P16 whereas it induced a metabolic shift in strain 18P13. However, this metabolic shift was not associated with enhancement of cellulose degradation. In contrast, an increase in cellulose breakdown was observed when strain 18P13 was cultivated with Ruminococcus hydrogenotrophicus. This stimulating effect could be attributed to both the autotrophic and the heterotrophic metabolism of the acetogen in the coculture.

Anaerobiosis↗

PubMed2001

Neutrophils, monocytes, and dendritic cells express the same specialized form of PSGL-1 as do skin-homing memory T cells: cutaneous lymphocyte antigen.

Memory T cells in inflamed skin express the cutaneous lymphocyte-associated antigen (CLA), a glycosylated epitope defined by the mAb HECA-452. We previously reported that on T cells, CLA occurs almost exclusively on the protein backbone of P-selectin glycoprotein ligand-1 (PSGL-1). T cells exhibiting the CLA isoform of PSGL-1 can tether and roll on both E- and P-selectin, while T cells expressing PSGL-1 without the CLA epitope do not bind E-selectin, though they may bind P-selectin. We show here that circulating neutrophils and monocytes, and cultured blood dendritic cells, also express CLA almost entirely as an isoform of PSGL-1. These cells all tether and roll on both E- and P-selectin. A chimeric fusion protein incorporating the 19 N-terminal amino acids of mature PSGL-1 exhibited HECA-452 immunoreactivity and supported rolling of CHO cells expressing either E- or P-selectin. These findings indicate a site for the CLA modification within the distal tip of PSGL-1, previously shown to be critical for P-selectin binding and to mediate some, but not all, of the E-selectin binding of PSGL-1. We hypothesize that the types of circulating leukocytes discussed above all use CLA/PSGL-1 to tether and roll on E- and P-selectin along the vascular endothelium.

Animals↗

PubMed2001

Highly optimized tolerance in epidemic models incorporating local optimization and regrowth.

In the context of a coupled map model of population dynamics, which includes the rapid spread of fatal epidemics, we investigate the consequences of two new features in highly optimized tolerance (HOT), a mechanism which describes how complexity arises in systems which are optimized for robust performance in the presence of a harsh external environment. Specifically, we (1) contrast global and local optimization criteria and (2) investigate the effects of time dependent regrowth. We find that both local and global optimization lead to HOT states, which may differ in their specific layouts, but share many qualitative features. Time dependent regrowth leads to HOT states which deviate from the optimal configurations in the corresponding static models in order to protect the system from slow (or impossible) regrowth which follows the largest losses and extinctions. While the associated map can exhibit complex, chaotic solutions, HOT states are confined to relatively simple dynamical regimes.

Journal Article↗

PubMed2001

MHC class I-related neonatal Fc receptor for IgG is functionally expressed in monocytes, intestinal macrophages, and dendritic cells.

The neonatal Fc receptor (FcRn) for IgG, an MHC class I-related molecule, functions to transport IgG across polarized epithelial cells and protect IgG from degradation. However, little is known about whether FcRn is functionally expressed in immune cells. We show here that FcRn mRNA was identifiable in human monocytes, macrophages, and dendritic cells. FcRn heavy chain was detectable as a 45-kDa protein in monocytic U937 and THP-1 cells and in purified human intestinal macrophages, peripheral blood monocytes, and dendritic cells by Western blot analysis. FcRn colocalized in vivo with macrosialin (CD68) and Ncl-Macro, two macrophage markers, in the lamina propria of human small intestine. The heavy chain of FcRn was associated with the beta(2)-microglobulin (beta(2)m) light chain in U937 and THP-1 cells. FcRn bound human IgG at pH 6.0, but not at pH 7.5. This binding could be inhibited by human IgG Fc, but not Fab. FcRn could be detected on the cell surface of activated, but not resting, THP-1 cells. Furthermore, FcRn was uniformly present intracellularly in all blood monocytes and intestinal macrophages. FcRn was detectable on the cell surface of a significant fraction of monocytes at lower levels and on a small subset of tissue macrophages that expressed high levels of FcRn on the cell surface. These data show that FcRn is functionally expressed and its cellular distribution is regulated in monocytes, macrophages, and dendritic cells, suggesting that it may confer novel IgG binding functions upon these cell types relative to typical Fc gamma Rs: Fc gamma RI, Fc gamma RII, and Fc gamma RIII.

Adult↗

PubMed2001

Homology between a 173-kb region from mouse chromosome 10, telomeric to the Ifng locus, and human chromosome 12q15.

We sequenced a 173-kb region of mouse chromosome 10, telomeric to the Ifng locus, and compared it with the human homologous sequence located on chromosome 12q15 using various sequence analysis programs. This region has a low density of genes: one gene was detected in the mouse and the human sequences and a second gene was detected only in the human sequence. The mouse gene and its human orthologue, which are expressed in the immune system at a low level, produce a noncoding mRNA. Nonexpressed sequences show a higher degree of conservation than exons in this genomic region. At least three of these conserved sequences are also conserved in a third mammalian species (sheep or cow).

Animals↗

PubMed2001

Sequence of the pig major histocompatibility region containing the classical class I genes.

A segment comprising 307,078 nucleotides of the pig major histocompatibility complex (SLA) was completely sequenced. The segment corresponded to the entire SLA classical class I-containing region of the serologically defined SLA H01 haplotype. In all, 11 genes were characterized, comprising 7 class I genes located on the centromeric part of the sequence (SLA-1, 2, 3, 4, 5, 9, and 11) and 4 ring finger-related family genes located on its telomeric part. No member of one family was intermingled with a member of the other or with any third-party gene. All class I genes except SLA-11 were similarly orientated. The SLA-1, 2, and 3 genes displayed both promoter and overall coding regions compatible with normal functions. The SLA-4, 11, and 9 genes were considered pseudogenes because they exhibited marked anomalies. Although the SLA-5 gene had a complete coding region, it displayed mutations in promoter elements which could modify its expression. The great molecular similarity observed among the class I genes extended far outside them, and resulted from segmental duplications. The ring finger genes exhibited great homology with their human counterparts. In pig, one of these genes appeared to correspond to a complete gene which in humans is probably a pseudogene. In all, the 11 genes characterized span about 20% of the total sequence. The remaining 80% consists of interspersed repeat elements. The present results, together with the sequence previously reported involving the SLA class I-related genes, open the way for a better understanding of pig MHC organization.

Alleles↗

PubMed2001

[Dural puncture in obstetric analgesia. Epidemiologic features and therapeutic management].

OBJECTIVE: To assess the time of occurrence, circumstances and presenting symptoms of unintentional dural puncture (UDP), the location and intensity of postdural puncture headaches (PDPH), and the efficacy of their treatment by epidural blood-patch (EBP). STUDY DESIGN: Cohort study. PATIENTS: Cases of UDP recorded over a 4-year period in an obstetric anaesthesia unit. METHODS: The following variables were studied: maternal age, weight and height, hour of occurrence and number of puncture attempts, existence of reflux of cerebrospinal fluid (CSF) through the needle, experience of the practitioners, subsequent modalities of obstetrical analgesia, frequency of occurrence, clinical characteristics and therapeutic management of PDPH. In case of EBP, the amount of blood and the efficacy of the procedure were also recorded. RESULTS: Twenty-one patients presented with UDP (0.66%). No reflux of CSF was identified in nine cases. Most UDP occurred at the first or second attempt, usually when performed by a practitioner poorly trained in epidural analgesia in obstetrics. The risk of UDP was higher during night-time work (risk ratio: 3.0; 95% confidence interval: 1.1-8.0; p = 0.04). Subsequent analgesia was provided via the epidural route in 19 cases, subarachnoidal route in one, and intravenous route in one case. PDPH did not develop in two patients. Three patients were given prophylactic EPB, and 16 received curative EBP. A second EBP was required 24 h later in seven patients. One patient developed meralgia paresthetica following EBP. CONCLUSION: In parturients, UDP usually results in PDPH. A rapid and effective treatment is required, mainly EBP. Another EBP is eventually necessary in some patients.

Analgesia, Epidural↗

PubMed2001

Development of a French inpatient satisfaction questionnaire.

OBJECTIVE: To develop a brief French-language, generic, self-administered questionnaire to measure inpatient satisfaction. DESIGN: Issues relevant to patients were identified using three open-ended questions designed in accordance with the disconfirmation paradigm. The content of patients' responses was analysed and then supplemented by items taken from published instruments in order to generate a pool of 93 items. Twenty-nine items were selected following a strict procedure. Content validity was judged by comparing the questionnaire to existing instruments. Construct validity was supported by testing specific hypotheses derived from the literature and by performing principal component analysis. Reliability was estimated by calculating Cronbach's alpha. SETTING: A 2200-bed French teaching hospital. SUBJECTS: A mail survey was carried out on a random sample of 1000 inpatients within 2-4 weeks of discharge. Eligible subjects were medical, surgical and obstetrics inpatients who had stayed in the hospital for more than 24 hours. RESULTS: The participation rate (71%) and the completion rate (95%) were indicators of acceptability. There were modest differences between the questionnaire and published instruments (financial aspects, amenities). Construct representation by principal component analysis consisted of six scales which accounted for 58% of the variance in total satisfaction scores. The reliability estimates of internal consistency ranged from 0.67 to 0.86. CONCLUSION: We propose that the self-administered multidimensional inpatient satisfaction questionnaire provided encouraging preliminary psychometric information. This instrument is intended to involve patient feedback in a continuous quality health care improvement strategy.

Adult↗

PubMed2001

Differential display and suppressive subtractive hybridization used to identify granulosa cell messenger rna associated with bovine oocyte developmental competence.

The main objective of this study was to identify mRNA expressed in the granulosa cells characterizing differentiated follicles bearing developmentally competent bovine oocytes. Analytical comparisons were made on mRNA pools of granulosa cells using differential display reverse transcription polymerase chain reaction (DDRT) analysis and suppressive subtractive hybridization (SSH). With DDRT, mRNA patterns of granulosa cells from small (< 4 mm) and large (> 8 mm) follicles cultured in the presence or absence of LH were compared to identify mRNA associated with follicular size or with the LH response. Nine clones were sequenced, and two were identified. One of the clones, DRAK 1, was associated with the presence of LH in the medium. Other comparisons directed toward the identification of mRNA associated with the presence of a competent oocyte were done on granulosa cells collected in vivo from superstimulated heifers. With the DDRT analysis, four clones associated with the oocyte developmental competence status were identified. With the SSH analysis, four clones specific to the presence of an incompetent oocyte were sequenced and none were identified, whereas 49 clones specific to the presence of a competent oocyte were sequenced and 18 were identified. Among these clones, early growth response 1, sprouty 2, cytochrome C oxidase, matrix metalloproteinase inducer, matrix metalloproteinase, epiregulin, prostaglandin receptor, and progesterone receptor were the most relevant to the ovarian physiology being examined.

Adenosine Triphosphatases↗

PubMed2001

Effects of treadmill speed on the mechanics of the back in the trotting saddlehorse.

Speed related changes in trunk mechanics have not yet been investigated, although high-speed training is currently used in the horse. To evaluate the effects of speed on back kinematics and trunk muscles activity, 4 saddle horses were recorded while trotting on a horizontal treadmill at speeds ranging from 3.5 to 6 m/s. The 3-dimensional (3-D) trajectories of skin markers on the left side of the horse and the dorsal midline of the trunk were established. Electrical activity was simultaneously obtained from the longissimus dorsi (LD) and rectus abdominis (RA) muscles using surface electrodes. Ten consecutive strides were analysed for each horse at each of the 5 velocity steps. Electromyographic and kinematic data were time-standardised to the duration of the stride cycle and compared using an analysis of variance. The back extended during the first part of each diagonal stance phase when the RA was active and the back flexed during the second part of each diagonal stance phase when the LD was active. The onset and end of muscle activity came earlier in the stride cycle and muscle activity intensity increased when speed increased. The amplitude of vertical movement of the trunk and the maximal angles of flexion decreased with increasing speed, whereas the extension angles remained unchanged. This resulted in a decreased range of back flexion-extension. This study confirms that the primary role of trunk muscles is to control the stiffness of the back rather than to induce movements. Understanding the effects of speed on the back of healthy horses is a prerequisite for the prevention and treatment of back pathology.

Animals↗

PubMed2001

Growth hormone secretagogues and hypothalamic networks.

Growth hormone secretagogues (GHSs) act at distinct levels to control growth hormone (GH) secretion. At the pituitary level they reinforce or extend a tonic GH-releasing-hormone (GHRH)-induced activated state by mobilizing intracellular Ca2+ store. At the hypothalamic level GHS actions are more complex than originally anticipated. Chronic treatments with GHS result in loss of responsiveness to the secretagogues, an effect probably accounted for by indirect negative feedback of GHS stimulated plasma GH levels over GHRH release. Moreover, intracerebroventricular treatments with GHS can have paradoxical, inhibitory effects on GH secretion. Several mechanisms can account for such dual effects. GHS receptors were found to extend far beyond the arcuate nucleus and are mainly coexpressed by GHRH, somatostatin, and neuropeptide Y (NPY) neurons. Activation of GHRH neurons by GHS can be direct or indirect. Indeed using antisense strategy we found that sstl are physiological activators of arcuate GHRH neurons and we propose that activation of SRIH arcuate interneurons by GHS can increase GHRH neuron activity. Moreover, GHS can stimulate distinct populations of NPY neurons having opposite effects on GH secretion: arcuate NPY interneurons, act as indirect facilitators of GHRH release, whereas, on the contrary, a different subset of NPY neurons projecting to the periventricular hypothalamus (those also involved in mediating leptin effects on GH) seems able to activate SRIH release.

Animals↗

PubMed2001

The effects of treadmill inclination and speed on the activity of three trunk muscles in the trotting horse.

The purpose of this study was to evaluate the effects of speed and slope on the activity of trunk muscles. The electromyographic (EMG) activity of the splenius (Sp), longissimus dorsi (LD) and rectus abdominis (RA) muscles was recorded with surface electrodes during treadmill locomotion at trot for different combinations of speed (3.5 to 6 m/s) and slope (0 to 6%). Raw EMG signals were processed to determine activity duration, onset and end and integrated EMG (IEMG). For the 3 muscles investigated, onset and end of activity were obtained earlier in the stride cycle when speed increased. A longer duration of activity for the LD, a shorter duration for the RA and an unchanged duration for the Sp were also observed. The IEMG of the latter was poorly affected by speed, whereas it increased linearly with speed for the 2 other muscles. When treadmill inclination changed from 0 to 6%, EMG activity of the LD and RA began and ended later; a longer activity duration was noted. Temporal parameters for Sp did not change with slope. A significant and progressive increase in the IEMG of the 3 muscles was observed with increasing slope. This evaluation of the activity of trunk muscles provides objective data for the use of speed or slope in training programmes.

Animals↗

PubMed2000

Genomic exploration of the hemiascomycetous yeasts: 11. Kluyveromyces lactis.

Random sequencing of the Kluyveromyces lactis genome allowed the identification of 2235-2601 open reading frames (ORFs) homologous to S. cerevisiae ORFs, 51 ORFs which were homologous to genes from other species, 64 tRNAs, the complete rDNA repeat, and a few Ty1- and Ty2-like sequences. In addition, the complete sequence of plasmid pKD1 and a large coverage of the mitochondrial genome were obtained. The global distribution into general functional categories found in Saccharomyces cerevisiae and as defined by MIPS is well conserved in K. lactis. However, detailed examination of certain subcategories revealed a small excess of genes involved in amino acid metabolism in K. lactis. The sequences are deposited at EMBL under the accession numbers AL424881-AL430960.

Ascomycota↗

PubMed2000

Sequence and analysis of chromosome 3 of the plant Arabidopsis thaliana.

Arabidopsis thaliana is an important model system for plant biologists. In 1996 an international collaboration (the Arabidopsis Genome Initiative) was formed to sequence the whole genome of Arabidopsis and in 1999 the sequence of the first two chromosomes was reported. The sequence of the last three chromosomes and an analysis of the whole genome are reported in this issue. Here we present the sequence of chromosome 3, organized into four sequence segments (contigs). The two largest (13.5 and 9.2 Mb) correspond to the top (long) and the bottom (short) arms of chromosome 3, and the two small contigs are located in the genetically defined centromere. This chromosome encodes 5,220 of the roughly 25,500 predicted protein-coding genes in the genome. About 20% of the predicted proteins have significant homology to proteins in eukaryotic genomes for which the complete sequence is available, pointing to important conserved cellular functions among eukaryotes.

Arabidopsis↗

PubMed2000

Identification of a key region of kinin B(1) receptor for high affinity binding of peptide antagonists.

To investigate the molecular basis for the specificity of ligand recognition in human kinin B(1) (B(1)R) and B(2) (B(2)R) receptors, we constructed a series of chimeric receptors by progressively replacing, from the N to the C terminus, the human B(2)R domains by their B(1) counterparts. The chimeric construct possessing the C-terminal tail and the transmembrane domain VII (TM VII) of the B(2)R (construct 6) displayed 7- and 20- fold decreased affinities for the B(1) agonist [(3)H]desArg(10)-kallidin (desArg(10)-KD) and the B(1) antagonist [(3)H]desArg(10)-[Leu(9)]-KD respectively, as compared with the wild-type B(1)R. Moreover, the substitution of the B(1) TM VII by its B(2) homologue TM increased the affinity for the pseudopeptide antagonists, Hoe140 and NPC 567. High affinity for desArg(10)-KD binding was fully regained when the B(2) residue Thr(287) was replaced in construct 6 by the corresponding B(1) Leu(294) residue. When the B(2) residue Tyr(295) was exchanged with the corresponding B(1) Phe(302), high affinity binding for both agonist and antagonist was recovered. Moreover, the L294T and F302Y mutant B(1)R exhibited 69- and 6.5-fold increases, respectively, in their affinities for the B(2) receptor antagonist, Hoe140. Therefore we proposed that Leu(294) and Phe(302) residues, which may not be directly involved in the binding of B(1)R ligands and, hence, their Thr(287) and Tyr(295) B(2) counterparts, are localized in a receptor region, which plays a pivotal role in the binding selectivity of the peptide or pseudopeptide kinin ligands.

Amino Acid Sequence↗

PubMed2000

Subtractive hybridization used to identify mRNA associated with the maturation of bovine oocytes.

The main objective of this project is to identify mRNA associated with oocyte maturation and embryonic developmental competency. The knowledge of genes and their accumulated mRNA is essential to better understand the mechanisms involved in the oocyte maturation and the survival of the in vitro produced embryo. We used bovine slaughterhouse-recovered ovaries and collected the oocytes from two follicle size categories: <2 mm and 3-5 mm. The mRNA content of oocytes from follicles 3-5 mm where considered to be more competent when compared to the content of oocytes from follicles <2 mm. In this report we compare two different technical approaches both involving PCR to compare the mRNA pools of the oocytes. In the first approach we performed the differential display (DDRT) technique to amplify and display side by side the cDNAs of groups of 10 denuded oocytes. From this approach, we isolated 28 different bands. After analysis, three of those bands had strong homology with known genes. In the second approach pools of 50 denuded oocytes were submitted to suppressive subtraction hybridization (SSH). We identified several known genes like cyclin B1, splicing factor ccl.4, cytochrome c oxidase, and mineralocorticoid receptor while numerous other clones remain unidentified. The cyclin B1 clone was used as a probe to evaluate its follicular size specificity on virtual Northern blot. The PCR basis of these techniques allows comparison of mRNA from tissues of low abundance such as oocytes. In this study the SSH resulted in longer clones than DDRT and showed high specificity.

Animals↗

PubMed2000

The gene encoding the mouse homologue of the human osteoclast-specific 116-kDa V-ATPase subunit bears a deletion in osteosclerotic (oc/oc) mutants.

Osteosclerosis (oc) is an autosomal recessive lethal mutation that impairs bone resorption by osteoclasts, and induces a general increase of bone density in affected mice. Genetic mapping of the oc mutation was used as a backbone in a positional cloning approach in the pericentromeric region of mouse chromosome 19. Perfect cosegregation of the osteopetrotic phenotype with polymorphic markers enabled the construction of a sequence-ready bacterial artificial chromosome (BAC) contig of this region. Genomic sequencing of a 200-kb area revealed the presence of the mouse homologue to the human gene encoding the osteoclast-specific 116-kDa subunit of the vacuolar proton pump. This gene was located recently on human 11q13, a genomic region conserved with proximal mouse chromosome 19. Sequencing of the 5' end of the gene in oc/oc mice showed a 1.6-kb deletion, including the translation start site, which impairs genuine transcription of this subunit. The inactivation of this osteoclast-specific vacuolar proton ATPase subunit could be responsible for the lack of this enzyme in the apical membranes of osteoclast cells in oc/oc mice, thereby preventing the resorption function of these cells, which leads to the osteopetrotic phenotype.

Amino Acid Sequence↗

PubMed2000

Empowerment and continuous improvement in the United States, Mexico, Poland, and India: predicting fit on the basis of the dimensions of power distance and individualism.

Although variations in national cultures predominate as explanation for the belief that universal approaches to management do not exist, there have been few reports of systematic studies. Data from employees of a single firm with operations in the United States, Mexico, Poland, and India were used to test the fit of empowerment and continuous improvement practices with national culture. Using the theoretical constructs of individualism-collectivism and power distance, the authors predicted that the practices would be more congruent in some cultures than in others and that value congruence would result in job satisfaction. Using structural equations modeling, the authors found that empowerment was negatively associated with satisfaction in India but positively associated in the other 3 samples. Continuous improvement was positively associated with satisfaction in all samples. Substantive, theoretical, and methodological implications are discussed.

Adolescent↗